Reversibly assembled cellular composite materials (RCCM) are three-dimensional lattices of modular structures that can be partially disassembled to enable repairs or other modifications.
[1][2] The discrete construction of reversibly assembled cellular composites introduces a new degree of freedom that determines global functional properties from the local placement of heterogeneous components.
They offer both a linear regime and a nonlinear super-elastic deformation mode a modulus an order of magnitude greater than for an ultralight material (12.3 megapascals at a density of 7.2 mg per cubic centimeter).
Site locations are locally constrained, yielding structures that merge desirable features of carbon fiber composites, cellular materials and additive manufacturing.
Elastic folding or pleating can occur in three dimensions, likely a coordinated antisymmetric twisting stress response and/or plastic deformation.
These results are consistent with the observation that open-cell lattice materials fail through micro-structural strut bending failures with σmax ∝.
The simulations also suggest that the coordinated buckling phenomenon as well as the modulus measurements are not dominated by edge effects, with minimal influence on overall results beyond characteristic lengths exceeding several units.
Examples of such truss cores have been reported with continuous two-dimensional (2D) geometric symmetry and nearly ideal but highly anisotropic specific modulus scaling.
Mass-produced cells can be assembled to fill arbitrary structural shapes, with a resolution prescribed by the part scale that matches the variability of an application's boundary stress.
[1] A “cuboct” cubic lattice of vertex connected octahedrons, similar to the perovskite mineral structure provides a regular polyhedral unit cell that satisfies Maxwell’s rigidity criterion and has a coordination number z of eight.
[1] Carbon-fiber reinforced composite materials can improve efficiency in engineered systems (for example, airframes) by reducing structural weight for given strength and stiffness requirements, but present challenges with manufacturing and certification.
Exact assembly of discrete cellular composites offers new properties and performance not available with the analog alternatives of continuously depositing or removing material.